Conventionally, a so-called tape streaming drive is known as a tape recording/reproducing apparatus capable of recording/reproducing digital data onto/from a magnetic tape. This kind of tape streaming drive can have a huge recording capacity of about several tens to several hundreds gigabyte, for example, depending on the tape length of the tape cassette. This drive is therefore widely used for backup of data recorded on a medium like a hard disk in a computer and the like. This drive is also said to be suitably used for storing image data of a large data size.
As a tape streaming drive as described above, for example, a proposal has been made for an apparatus which uses a tape cassette for 8 mm-VTR as a recording medium and adopts a helical scan system based on a rotary head to record/reproduce data.
In the tape streaming drive using a 8 mm VTR tape cassette as described above, for example, SCSI (Small Computer System Interface) is used for the input/output interface for recording/reproducing data.
When recording data, for example, data supplied from a host computer is inputted through the SCSI interface. This input data is transferred in units of data groups each having a predetermined fixed length. The inputted data is subjected to compression processing if necessary and is then buffered in a buffer memory. The data buffered in the buffer memory is supplied to the recording/reproducing system, in units of data each having a fixed length, and recording onto a magnetic tape of a tape cassette is carried out by a rotary head.
When reproducing data, data on a magnetic tape is read by a rotary head and is once buffered in a buffer memory. The data from the buffer memory is subjected to expansion processing if the data has been subjected to compression processing when recording, and the data is then transferred to a host computer.
Each data recording region on the magnetic tape forms a numbered partition, and data can be reproduced therefrom or written thereinto.
To make appropriate recording/reproducing operation on a magnetic tape in a tape cassette in a data storage system using a tape streaming drive and a tape cassette as described above, various position information items on the magnetic tape and information items related to use history of the magnetic tape are necessary as management information which the tape streaming drive uses for management of recording/reproducing operation. These information items include the number of the latest used partition.
Hence, it has been discussed to store the management information into a memory means such as a memory chip separated from the magnetic tape. This memory means is attached to a part of an outer surface of the tape cassette.
In the side of the tape streaming drive, necessary management information items are read by accessing the memory means before making operation of recording or reproducing data with respect to the magnetic tape. Subsequent recording/reproducing operation is carried out properly based on the management information items. After recording or reproducing operation is finished, the memory means is accessed again to overwrite the contents of the management information, in order to overwrite the contents of the management information which need to be updated in accordance with the recording or reproducing operation. The system thus becomes ready for next recording/reproducing operation. Thereafter, the tape cassette is unloaded or ejected by the tape streaming drive.
Meanwhile, in case where recording data is recorded on a data recording region having a plurality of partitions formed on a magnetic tape, as described above, numbers are designated to the partitions in the descending order from the beginning of the tape (BOT) toward the end of the tape (EOT) of the tape-like recording medium as shown in FIG. 26. If eight partitions are formed, the partition numbers thereof are P.sub.7, P.sub.6, P.sub.5, P.sub.4, P.sub.3, P.sub.2, P.sub.1, and P.sub.0 from the beginning of the tape-like recording medium. This is because the total number of the partitions can be estimated from the first partition number formed at the beginning of the tape-like recording medium.
However, if the last partition of the tape-like recording medium is deleted from the partition numbers thus designated in the descending order, i.e., if the last partition is merged with the partition immediately before the partition itself, the total number of the partitions formed on the tape-like recording medium cannot be estimated from the first partition number at the beginning of the tape-like recording medium.
Thus, this kind of data storage system is based on the prerequisite that partitions may not be deleted. Therefore, all the partitions except for the last partition need to be preformatted before recording the recording data. Since the pre-formatting must be performed substantially over the entire tape-like recording medium, the longer time is required as the data capacity of the tape-like recording medium increases. For example, if continuous transfer rate is 2 Mbyte/sec, 10,000 seconds or more or about three hours data capacity are required to pre-format a tape-like recording medium having a data capacity of 20 Gbyte.